Rotary compressor

ABSTRACT

A sealing ring is provided between an end plate of an eccentric rotation body and a support plate so that a pressure of fluid at high pressure is allowed to work on the end plate, thereby allowing an axial-direction pressing force to work on the end plate. The sealing ring is arranged eccentrically away from the a center of a cylinder as forming the eccentric rotation body to minimize separation of the axial-direction pressing force from a thrust load in the a radial direction in the end plate of, thereby reducing turnover moment effectively.

TECHNICAL FIELD

The present invention relates to a rotary compressor and moreparticularly relates to a rotary compressor including a cylinder havinga cylinder chamber, a piston eccentrically accommodated in the cylinderchamber, and a pressing mechanism for bringing a cylinder side end plateand a piston side end plate close to each other.

BACKGROUND ART

As one of conventional rotary compressors including a compressionmechanism in which a piston (an eccentric rotation body) rotateseccentrically within a cylinder chamber, there has been proposed arotary compressor in which refrigerant is compressed by volume change ofthe cylinder chamber in association with eccentric rotation of anannular piston (for example, see Patent Document 1).

In the compressor (100), a hermetic casing (110) accommodates acompression mechanism (120) and a drive mechanism (an electric motor)(not shown) for driving the compression mechanism (20), as shown in FIG.12 and FIG. 13 (a section taken along the line XIII-XIII in FIG. 12).

The compression mechanism (120) includes a cylinder (121) having anannular cylinder chamber (C1, C2) and an annular piston (122) arrangedin the cylinder chamber (C1, C2). The cylinder (121) includes an outercylinder (124) and the inner cylinder (125) which are arranged coaxiallyso that the cylinder chamber (C1, C2) is formed between the outercylinder (124) and the inner cylinder (125). The outer cylinder (124)and the inner cylinder (125) are integrated by means of a cylinder sideend plate (126A) provided at the top end faces thereof.

The annular piston (122) is connected to an eccentric portion (133 a) ofa drive shaft (133) connected to the electric motor through a pistonbase (piston side end plate) (126B) in substantially a circular shape soas to rotate eccentrically away from the center of the drive shaft(133). The annular piston (122) eccentrically rotates while beingsubstantially in contact at one point of the outer peripheral facethereof with the inner peripheral face of the outer cylinder (124)(wherein, “substantially in contact” means a state in which though aminute gap is present to an extent that an oil film is formed, leakageof refrigerant in the gap is ignorable) and keeping substantially incontact at one point of the inner peripheral face 180° different inphase from the contact point with the outer peripheral face of the innercylinder (125). Thus, an outer cylinder chamber (C1) and an innercylinder chamber (C2) are formed on the outside and the inside of theannular piston (122), respectively.

An outer blade (123A) is arranged outside the annular piston (22). Theouter blade (123A) is forced inward in the radial direction of theannular piston (122) so that the inner peripheral end thereof pushes andis in contact with the outer peripheral face of the annular piston(122). The outer blade (123A) divides the outer cylinder chamber (C1)into a high pressure chamber (a first chamber) (C1-Hp) and a lowpressure chamber (a second chamber) (C1-Lp).

On the other hand, an inner blade (123B) is arranged inside the annularpiston (123) on an extension line of the outer blade (123A). The innerblade (123B) is forced outward in the radial direction of the annularpiston (122) so that the outer peripheral end thereof pushes and is incontact with the inner peripheral face of the annular piston (122). Theinner blade (123B) divides the inner cylinder chamber (C2) into a highpressure chamber (a first chamber) (C2-Hp) and a low pressure chamber (asecond chamber) (C2-Lp).

Further, in the outer cylinder (124), an intake port (141) for allowingthe outer cylinder chamber (C1) to communicate with an intake pipe (114)provided at a casing (110) is formed in the vicinity of the outer blade(123A). Also, in the annular piston (122), a through hole (143) isformed in the vicinity of the intake port (141) so that the low pressurechamber (C1-Lp) of the outer cylinder chamber (C1) and the low pressurechamber (C2-Lp) of the inner cylinder chamber (C2) communicate with eachother through the through hole (143). Further, a discharge port (notshown) for allowing the high pressure chambers (C1-Hp, C2-Hp) of thecylinder chambers (C1, C2) to communicate with a high pressure space (S)in the casing (110) is formed in the compression mechanism (120).

In the thus constructed compressor (100), when the drive shaft (133)rotates to eccentrically rotate the annular piston (122), volumeexpansion and contraction are repeated alternately in both the outercylinder chamber (C1) and the inner cylinder chamber (C2). In the volumeexpansion of the respective cylinder chambers (C1, C2), a suckingprocess is performed in which the refrigerant is sucked into therespective cylinder chambers (C1, C2) from the intake port (141). Whilein the volume contraction, a compression process in which therefrigerant is compressed in the respective cylinder chambers (C1, C2)and a discharge process in which the refrigerant is discharged from therespective cylinder chambers (C1, C2) to the high pressure space (S) inthe casing (110) through the discharge port are performed. Thus, therefrigerant at high pressure discharged in the high pressure space (S)of the casing (110) flows into a condenser of a refrigeration circuitthrough a discharge pipe (115) provided in the casing (110).

In the compressor (100) in this case, a support plate (117) forsupporting the piston side end plate (126B) is formed at the lower faceof the end plate (126B) connected to the annular piston (122). A sealingring (129) is provided coaxially with the annular piston (122) at a partwhere the piston side end plate (126B) faces the support plate (117).The piston side end plate (126B) receives at a part thereofcorresponding to the inner peripheral side of the sealing ring (129)pressure of the refrigerant in the high pressure space (S). This causesthe piston side end plate (126B) to push upward in the axial directiontowards the cylinder (121) to minimize gaps in the axial directionbetween the cylinder (121) and the annular piston (123) (a firstaxial-direction gap between the lower end face in the axial direction ofthe cylinder (121) and the piston side end plate (126B) and a secondaxial-direction gap between the upper end face in the axial direction ofthe piston (122) and the cylinder side end plate (126A)).

Patent Document 1: Japanese Patent Application Laid Open Publication No.6-288358A

DISCLOSURE OF THE INVENTION Problem that the Invention is to Solve

In the conventional construction as shown in FIG. 12 and FIG. 13, whenpressure in the cylinder chambers (C1, C2) become high in thecompression process, for example, gas force (a downward thrust load) inthe axial direction is liable to work on the piston side end plate(126B) formed at the lower end of the annular piston (122). If thethrust load would become large or a point of action of the thrust loadwould be away from the axial center of the drive shaft (133), the pistonside end plate (126B) and the annular piston (122) fixed to the endplate (126B) may incline (be turned over) with respect to the driveshaft (133) when a moment (a turnover moment) working on the piston sideend plate (126B) exceeds a predetermined value. When a gap is generatedbetween the annular piston (122) and the cylinder (121) by such turnoverof the annular piston (122), the refrigerant leaks through the gap tolower the compression efficiency.

In the above conventional construction, the turnover moment caused dueto the thrust load might be mitigated in such a manner that pressingforce in the axial direction, which is obtained from the pressure at thepart of the piston side end plate (126B) corresponding to the innerperipheral side of the sealing ring (129), works on the piston side endplate (126B) against the thrust load. However, the mitigation isinsufficient because of the following reasons.

FIG. 14 is an explanatory drawing showing step by step eccentric motionof the annular piston (122) in the conventional construction. By drivingthe drive shaft (133), the annular piston (122) eccentrically rotateswithin the cylinder chamber (C1, C2) in the order shown in FIG. 14(A) toFIG. 14(D). When the annular piston (122) is in the state shown in FIG.14(A), the pressure of the refrigerant in the high pressure chamber(C2-Hp) of the inner cylinder chamber (C2) rises to allow the center ofthe thrust load (PT) to move on the upper face of the piston side endplate (126B) towards the high pressure chamber (C2-Hp) in the radialdirection, as shown by the arrow (PT) in FIG. 14. In contrast to thethrust load (PT), the pressing force (the arrow (P) in FIG. 14) obtainedfrom the sealing ring (129) is centered on the center of the sealingring (129) on the lower face of the piston side end plate (126B), inother words, on the center of the annular piston (122). This means thatthe point of action of the axial-direction pressing force (P) isdifferent in the radial direction from the point of action of the thrustload (PT) working on the piston side end plate (126B), causingdifficulty in effective mitigation of the turnover moment.

Further, in the state shown in FIG. 14(B) in which the inner pressure ofthe high pressure chamber (C2-Hp) of the inner cylinder chamber (C2)becomes high and the inner pressure of the high pressure chamber (C1-Hp)of the outer cylinder chamber (C1) becomes slightly high, the thrustload (PT) works on a part near the high pressure chambers (C1-Hp, C2-Hp)while the axial-direction pressing force (P) obtained from the sealingring (129) works on a part near the low pressure chamber (C2-Lp), whichis the center of the annular piston (122). Accordingly, the point ofaction of the axial-direction pressing force (P) further separates fromthe point of action of the thrust load (PT), inviting further difficultyin mitigation of the turnover moment.

In addition, in the state shown in FIG. 14(D) in which the innerpressure of the high pressure chamber (C1-Hp) of the outer cylinderchamber (C1) becomes high and the inner pressure of the high pressurechamber (C2-Hp) of the inner cylinder (C2) becomes slightly high, thethrust load (PT) is centered at a part near the high pressure chambers(C1-Hp, C2-Hp), resulting in separation of the point of action of theaxial-direction pressing force (P) from the point of action of thethrust load (PT) to invite difficulty in effective mitigation of theturnover moment, as well.

As described above, in the conventional construction, theaxial-direction pressing force (P) obtained from the sealing ring (129)hardly agrees with the thrust load (PT) in eccentric rotation of theannular piston (122), attaining ineffective restraint on turnover of theannular piston (122).

The present invention has been made in view of the above problems andhas its objective of restraining turnover of an eccentric rotation bodysuch as an annular piston by effectively exerting axial-direction forceagainst a thrust load working on a end plate of the eccentric rotationbody.

Means of Solving the Problems

In the present invention, axial-direction pressing force to work on aend plate is made to work eccentrically from the center of an eccentricrotation body.

Specifically, the first invention provides a rotary compressor includes:a compression mechanism (20) including a cylinder (21) having a cylinderchamber (C) (C1, C2), a piston (22) accommodated in the cylinder chamber(C) (C1, C2) eccentrically with respect to the cylinder (21), and ablade (23) arranged in the cylinder chamber (C) (C1, C2) and definingthe cylinder chamber (C) (C1, C2) into a first chamber (C-Hp) (C1-Hp,C2-Hp) and a second chamber (C-Lp) (C1-Lp, C2-Lp), at least one of thecylinder (21) and the piston (22) rotating eccentrically as an eccentricrotation body (21, 22); a drive shaft (33) for driving the compressionmechanism (20); a pressing mechanism (60) for bringing a cylinder sideend plate (26A), which is provided at one end in an axial direction ofthe cylinder chamber (C) (C1, C2) and faces an end face in an axialdirection of the piston (22), and a piston side end plate (26B), whichis provided at the other end in the axial direction of the cylinderchamber (C) (C1, C2) and faces an end face in an axial direction of thecylinder (21), close to each other in an axial direction of the driveshaft (33); and a casing (10) for accommodating the compressionmechanism (20), the drive shaft (33), and the pressing mechanism (60),wherein the pressing mechanism (60) is eccentric away from the center ofthe end plate (26A, 26B) of the eccentric rotation body (21, 22), andthe pressing mechanism (60) generates axial-direction pressing force ofwhich center is eccentric away from the center of the drive shaft (33).Wherein, “a part eccentric from the center of the end plate (26A, 26B)of the eccentric rotation body (21, 22) and eccentric from the center ofthe drive shaft (33)” is shortened to “a part eccentric from the centerof the end plate (26A, 26B) of the eccentric rotation body (21, 22)” inthe following description.

In the first invention, the eccentric rotation body (21, 22)eccentrically rotates by the drive shaft (33) to change each volume ofthe first chamber (C-Hp) (C1-Hp, C2-Hp) and the second chamber (C-Lp)(C1-Lp, C2-Lp) in the cylinder chamber (C) (C1, C2), resulting incompression of to-be-processed fluid. In the compression, the pressingmechanism (60) brings the piston side end plate (26B) and the cylinderside end plate (26A) close to each other in the axial direction tominimize gaps in the axial direction between the piston (22) and thecylinder (21) (a first axial-direction gap between the end face in theaxial direction of the cylinder (21) and the piston side end plate (26B)and a second axial-direction gap between the end face in the axialdirection of the piston (22) and the cylinder side end plate (26A)).

In this invention, the resultant force of the axial-direction pressingforce obtained from the pressing mechanism (60) is centered at a parteccentric from the center of the end plate (26A, 26B) of the eccentricrotation body (21, 22). Thus, separation in the axial direction of thepoint of action of the axial-direction pressing force (P) from the pointof action of the thrust load (PT) is restrained, which is the differencefrom the aforementioned conventional technique. As a result, theturnover moment caused due to the thrust load (PT) can be restrainedeffectively.

Referring to the second invention, in the rotary compressor of the firstinvention, the cylinder chamber (C) is in a circular shape in section ata right angle in an axial direction, and the piston (22) is formed of acircular piston (22) arranged in the cylinder chamber (C). Wherein, “thesection at a right angle in the axial direction” herein means a sectionat a right angle with respect to the drive shaft (the rotation center).

In the second invention, in the rotary compressor in which the cylinderchamber (C) has a circular shape in section at a right angle in theaxial direction and the piston (22) is formed of a circular piston (22),the resultant force of the axial-direction pressing force obtained fromthe pressing mechanism (60) is centered at a part eccentric from thecenter of the end plate (26A, 26B) of the eccentric rotation body (21,22), so that separation in the axial direction of the point of action ofthe axial-direction pressing force (P) from the point of action of thethrust load (PT) is restrained, restraining the turnover moment causeddue to the thrust load (PT) effectively.

Referring to the third invention, in the rotary compressor of the firstinvention, the cylinder chamber (C1, C2) is in an annular shape insection at a right angle in an axial direction, and the piston (22) isformed of an annular piston (22) arranged in the cylinder chamber (C1,C2) and defining the cylinder chamber (C1, C2) into an outer cylinderchamber (C1) and an inner cylinder chamber (C2).

In the third invention, the annular piston (22) is arranged in theannular cylinder chamber (C1, C2) to form an outside cylinder chamber(the outer cylinder chamber) (C1) between the wall face on the outerperipheral side of the cylinder chamber (C1, C2) and the outerperipheral face of the annular piston (22) and an inside cylinderchamber (the inner cylinder chamber) (C2) between the wall face on theinner peripheral side of the cylinder chamber and the inner peripheralface of the annular piston (22). As a result, the rotary compressor canbe attained in which the to-be-processed fluid is compressed byalternate repetition of volume expansion and contraction in both theouter cylinder chamber (C1) and the inner cylinder chamber (C2),similarly to the aforementioned conventional rotary compressor.

In this invention, similarly to the first and second inventions, theresultant force of the axial-direction pressing force obtained from thepressing mechanism (60) is centered at a part eccentric from the centerof the end plate (26A, 26B) of the eccentric rotation body (21, 22), sothat separation in the axial direction of the point of action of theaxial-direction pressing force (P) from the point of action of thethrust load (PT) is restrained, resulting in effective restraint on theturnover moment caused due to the thrust load (PT).

Referring to the fourth invention, in the rotary compressor of the thirdinvention, the piston (22) is in a C-shape into which a part of anannular shape is divided, a swing bush (27) is provided so as to beslidably held at the divided part of the piston (22), a blade groove(28) being formed therein for holding a blade (23) so as to allow theblade (23) to move back and forth, and the blade (23) is inserted in theblade groove (28) so as to extend from a wall face on an innerperipheral side to a wall face on an outer peripheral side of theannular cylinder chamber (C1, C2).

In the fourth invention, when at least one of the cylinder (21) and thepiston (22) eccentrically rotates as the eccentric rotation body (21,22), the blade (23) moves back and forth with the face thereof being inface contact with the blade groove (28) in the swing bush (27) while theswing bush (27) rocks with the face thereof being in face contact withthe divided part of the piston (22). Thus, the cylinder chambers (C1,C2) can be divided into first chambers (C1-Hp, C2-Hp) and secondchambers (C2-Lp, C2-Lp) while the blade (23) moves smoothly in theeccentric rotation of the eccentric rotation body (21, 22).

Referring to the fifth invention, in the rotary compressor of the firstinvention, discharge ports (45, 46) for discharging fluid compressed inthe cylinder chamber (C1, C2) to outside of the compression mechanism(20) are formed in the compression mechanism (20), and the pressingmechanism (60) generates the axial-direction pressing force of whichcenter is eccentric to the discharge ports (45, 46) away from the centerof the end plate (26A, 26B) of the eccentric rotation body (21, 22).

In the fifth invention, the to-be-processed fluid at high pressure bycompression in, for example, the first chambers (C1-Hp, C2-Hp) isdischarged outside the compression mechanism (20) through the dischargeports (45, 46).

In this invention, the center of the resultant force of theaxial-direction pressing force is set at a part near the discharge ports(45, 46) in the end plate (26A, 26B) of the eccentric rotation body (21,22) where the to-be-processed fluid is liable to be at high pressure andwhere the thrust load (PT) working on the end plate (26A, 26B) of theeccentric rotation body (21, 22) is liable to be large. Accordingly, thepoint of action of the axial-direction pressing force (P) readily agreeswith the point of action of the thrust load (PT) in the axial direction,with a result that the turnover moment cuased due to the thrust load(PT) can be restrained further effectively.

Referring to the sixth invention, in the rotary compressor of the firstinvention, wherein a support plate (17) is arranged along a faceopposite a face on the cylinder chamber (C1, C2) side of the end plate(26A, 26B) of the eccentric rotation body (21, 22) in the casing (10), asealing ring (29) for defining an opposing part (61, 62) between the endplate (26A, 26B) and the support plate (17) inside and outside in aradial direction into a first opposing section (61) and a secondopposing section (62) is arranged eccentrically away from the center ofthe eccentric rotation body (21, 22) in one of the end plate (26A, 26B)of the eccentric rotation body (21, 22) and the support plate (17), andthe pressing mechanism (60) allows pressure of fluid discharged outsidethe compression mechanism (20) to work on the first opposing section(61) in the end plate (26A, 26B).

In the sixth invention, the sealing ring (29) is provided between theend plate (26A, 26B) of the eccentric rotation body (21, 22) and thesupport plate (17) to partition an opposing part between the end plate(26A, 26B) of the eccentric rotation body (21, 22) and the support plate(17) into two or more opposing sections (61, 62). The fluid at highpressure in the compression mechanism (20) is introduced into the firstopposing section (61) and the pressure of the fluid is allowed to workon the first opposing section (61) in the end plate (26A, 26B) of theeccentric rotation body (21, 22), thereby obtaining the axial-directionpressing force against the end plate (26A, 26B) of the eccentricrotation body (21, 22).

In the present invention, the sealing ring (29) is provided at a parteccentric from the center of the eccentric rotation body (21, 22), sothat the axial-direction pressing force obtained from the sealing ring(29) is centered at a part eccentric from the center of the end plate(26A, 26B) of the eccentric rotation body (21, 22). This restrainsseparation of the point of action of the axial-direction pressing force(P) from the point of action of the thrust load (PT), as describedabove.

Referring to the seventh invention, in the rotary compressor of thesixth invention, the sealing ring (29) is fitted in an annular groove(17 b) formed in one of the eccentric rotation body (21, 22) and thesupport plate (17).

In the seventh invention, the sealing ring (29) is fitted in the annulargroove (17 b), thereby being held securely at a position eccentric fromthe center of the eccentric rotation body (21, 22).

Referring to the eighth invention, in the rotary compressor of the firstinvention, wherein a slit (63) is formed at a part eccentric away fromthe center of the eccentric rotation body (21) in a face portionopposite a face on the cylinder chamber (C1, C2) side of the end plate(26A) of the eccentric rotation body (21), and the pressing mechanism(60) allows pressure of fluid discharged outside the compressionmechanism (20) to work on the slit (63).

In the eight invention, the pressure of the fluid at high pressure inthe compression mechanism (20) is allowed to work on the slit (63) tocause the axial-direction pressing force (P) to readily work in thevicinity of the slit (63) in the end plate (26A) of the eccentricrotation body (21). In this invention, the slit (63) to be formed at apart eccentric from the center of the eccentric rotation body (21). Thisallows the axial-direction pressing force obtained according to theshape of the slit (63) is centered at a part of the end plate (26A)eccentric from the center of the eccentric rotation body (21).Accordingly, separation of the point of action of the axial-directionpressing force (P) from the point of action of the thrust load (PT) inthe axial direction is restrained.

Referring to the ninth invention, in the rotary compressor of the firstinvention, wherein a groove (65) and a through hole (64) are formed, thegroove (65) being formed in a portion eccentric away from the center ofthe eccentric rotation body (21) on a face opposite a face on thecylinder chamber (C1, C2) side of the end plate (26A) of the eccentricrotation body (21) and the through hole (64) being formed in the endplate (26A) for allowing the groove (65) to communicate with thecylinder chamber (C) (C1, C2), and the pressing mechanism (60)introduces part of fluid compressed in the cylinder chamber (C1, C2)into the groove (65) through the through hole (64) to allow the pressureof the fluid to work on the groove (65).

In the ninth invention, part of the fluid compressed in the compressionmechanism (20) is introduced into the groove (65) through the throughhole (64), so that the axial-direction pressing force readily works inthe vicinity of the groove (65) in the end plate (26A) of the eccentricrotation body (21). In this invention, the groove (65) is formed in apart eccentric from the center of eccentric rotation body (21). Thisallows the axial-direction pressing force obtained according to theshape of the grove (65) to be centered at a part of the end plate (26A)eccentric from the center of the eccentric rotation body (21).Accordingly, separation of the point of action of the axial-directionpressing force (P) from the point of action of the thrust load (PT) inthe axial direction is restrained.

Referring to the tenth invention, the rotary compressor of the firstinvention further includes: a sealing mechanism (71, 72, 73) forpreventing leakage of fluid in at least one of a first axial directiongap between an end face in the axial direction of the cylinder (21) andthe piston side end plate (26B) and a second axial direction gap betweenan end face in the axial direction of the piston (22) and the cylinderside end plate (26A).

In the tenth invention, the sealing mechanism for minimizing theaxial-direction gaps between the cylinder (21) and the piston (22) isprovided in addition to the aforementioned pressing mechanism (60), sothat the fluid at high pressure in, for example, the first chambers(C1-Hp, C2-Hp) is prevented from leaking into the second chambers(C1-Lp, C2-Lp) through the axial-direction gaps in the eccentricrotation of the eccentric rotation body (21, 22).

Referring to the eleventh invention, in the rotary compressor of thetenth invention, the sealing mechanism is a chip seal (71, 72, 73)provided at least one of the first axial direction gap and the secondaxial direction gap.

In the tenth invention, the chip seal (71, 72, 73) is provided at atleast one of the first axial-direction gap and the secondaxial-direction gap between the cylinder (21) and the piston (22),minimizing the axial-direction gaps to prevent the fluid in the gapsform leaking.

EFFECTS OF THE INVENTION

According to the first invention, in the compression mechanism (20)including the cylinder (21) having the cylinder chamber (C1) (C1, C2)and the piston (22), the pressing mechanism (60) minimizes theaxial-direction gaps between the piston (22) and the cylinder (21), andthe eccentric rotation body (21, 22) eccentrically rotates to allow theaxial-direction pressing force (P) to work against the thrust load (PT)caused in the cylinder chamber (C) (C1, C2). Working of theaxial-direction pressing force (P) on the end plate (26A, 26B) with thecenter thereof being eccentric from the center of the eccentric rotationbody (21, 22) minimizes separation of the axial-direction pressing force(P) from the thrust load (PT) in the radial direction, therebyrestraining the turnover moment effectively.

According to the second invention, in the compression mechanism (20)including the cylinder (21) having the circular cylinder chamber (C1)and the circular piston (22), the pressing mechanism (60) minimizes theaxial-direction gaps between the piston (22) and the cylinder (21), andthe eccentric rotation body (21, 22) eccentrically rotates to allow theaxial-direction pressing force (P) to work against the thrust load (PT)caused in the cylinder chamber (C1). Working of the axial-directionpressing force (P) on the end plate (26A, 26B) with the center thereofbeing eccentric from the center of the eccentric rotation body (21, 22)minimizes separation of the axial-direction pressing force (P) from thethrust load (PT) in the radial direction, thereby restraining theturnover moment effectively.

According to the third invention, in the compression mechanism (20)including the cylinder (21) having the annular cylinder chamber (C1, C2)and the annular piston (22), the pressing mechanism (60) minimizes theaxial-direction gaps between the piston (22) and the cylinder (21), andthe eccentric rotation body (21, 22) eccentrically rotates to allow theaxial-direction pressing force (P) to work against the thrust load (PT)caused in the cylinder chamber (C1, C2). Working of the axial-directionpressing force (P) on the end plate (26A, 26B) with the center thereofbeing eccentric from the center of the eccentric rotation body (21, 22)minimizes separation of the axial-direction pressing force (P) from thethrust load (PT) in the radial direction, thereby restraining theturnover moment effectively.

According to the fourth invention, in the rotary compressor of the thirdinvention, the blade (23) moves back and forth with the face thereofbeing in face contact with the blade groove (28) in the swing bush (27)while the swing bush (27) rocks at the divided part of the piston (22),enabling the eccentric rotation body (21, 22) to be in smooth eccentricrotation with the cylinder chamber (C1, C2) divided. Hence, seizing andabrasion at the contact part between the blade (23) and the swing bush(27) can be prevented and gas is prevented from leaking between thefirst chamber (C1-Hp, C2-Hp) and the second chamber (C2-Lp, C2-Lp).

In the fifth invention, the axial-direction pressing force (P) againstthe end plate (26A, 26B) obtained from the pressing mechanism (60) isallowed to work on a part near the discharge ports (45, 46), which isliable to receive the thrust load (PT) in the cylinder chamber (C1, C2).Accordingly, the point of action of the axial-direction pressing force(P) can be brought close to the point of action of the thrust load (PT),reducing the turnover moment further effectively.

According to the sixth invention, the pressing mechanism (60) is socomposed that the pressure of the fluid at high pressure is allowed towork on the first opposing section (61) into which the end plate (26A,26B) is defined by the sealing ring (69). The pressing mechanism (60) iseasily composed by arranging the sealing ring (69) eccentrically fromthe center of the eccentric rotation body (21, 22), attaining effectivereduction in turnover moment. Thus, the effect of reducing the turnovermoment can be obtained with the simple construction.

Further, the sealing ring (29) prevents the refrigerant in the cylinderchamber (C) (C1, C2) from leaking outside the compression mechanism (20)from the first opposing section (61) between the support plate (17) andthe end plate (26A, 26B).

According to the seventh invention, the annular groove (17 b) is formedin the piston (22) or the support plate (17), so that the sealing ring(29) can be held securely at a predetermined position.

According to the eight invention, the pressing mechanism (60) is socomposed that the pressure of the fluid at high pressure is allowed towork on the slit (63) formed in the end plate (26A). The pressingmechanism (60) is easily composed by forming the slit (63) eccentricallyfrom the center of the eccentric rotation body (21), attaining effectivereduction in turnover moment. Thus, the effect of reducing the turnovermoment can be obtained with the simple construction.

Further, the slit (63) is formed easily by forming a step in the endplate (26A), which means that the end plate (26A) in which the slit (63)is formed can be integrally formed with the eccentric rotation body (21)by, for example, sintering or forging.

According to the ninth invention, the pressing mechanism (60) is socomposed that part of the fluid compressed in the cylinder chamber (C1,C2) is allowed to work on the groove (65) through the through hole (64).The pressing mechanism (60) can be easily composed by forming the groove(65) eccentrically from the center of the eccentric rotation body (21),attaining effective reduction in turnover moment.

Further, according to this invention, as the pressure in the cylinderchamber (C1, C2) rises and the thrust load (PT) becomes large, theaxial-direction pressing force (P) working on the groove (65) increases.In contrast, when the thrust load (PT) becomes small, theaxial-direction pressing force (P) decreases. Hence, an increase inmechanical loss of the eccentric rotation body (21), which is caused dueto surplus axial-direction pressing force (P), is prevented,implementing effective reduction in turnover moment.

According to the tenth invention and the eleventh invention, the sealingmechanism (71, 72, 73) is provided in addition to the pressing mechanism(60), so that the fluid is prevented from leaking in the axial-directiongaps between the cylinder (21) and the piston (22), further increasingthe compression efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical section of a rotary compressor according toEmbodiment 1.

FIG. 2 is a transverse section of a compression mechanism.

FIG. 3 shows transverse sections illustrating operation of thecompression mechanism.

FIG. 4 shows transverse sections illustrating operation of a compressionmechanism of a rotary compressor according to Modified Example 1 ofEmbodiment 1.

FIG. 5 is a vertical section of a compression mechanism of a rotarycompressor according to Modified Example 2 of Embodiment 1.

FIG. 6 is a vertical section of a compression mechanism of a rotarycompressor according to Modified Example 3 of Embodiment 1.

FIG. 7 is a vertical section of a rotary compressor according toEmbodiment 2.

FIG. 8 shows transverse sections illustrating operation of a compressionmechanism.

FIG. 9 is a vertical section of a rotary compressor according toEmbodiment 3.

FIG. 10 is a vertical section of a rotary compressor according toModified Example of Embodiment 3.

FIG. 11 is a vertical section of a compression mechanism of a rotarycompressor according to another embodiment.

FIG. 12 is a vertical section in part of a rotary compressor accordingto a conventional technique.

FIG. 13 is a section taken along the line XIII-XIII in FIG. 12.

FIG. 14 shows transverse sections illustrating operation of acompression mechanism.

DESCRIPTION OF REFERENCE NUMERALS

-   -   1 compressor    -   10 casing    -   17 lower housing (support plate)    -   20 compression mechanism    -   21 cylinder    -   22 piston    -   23 blade    -   26A cylinder side end plate    -   26B piston side end plate    -   27 swing bush    -   29 sealing ring    -   33 drive shaft    -   C1 cylinder chamber (outer cylinder chamber)    -   C2 cylinder chamber (inner cylinder chamber)    -   C1-Hp first chamber (high pressure chamber)    -   C2-Hp first chamber (high pressure chamber)    -   C1-Lp second chamber (low pressure chamber)    -   C2-Lp second chamber (low pressure chamber)    -   45, 46 discharge port    -   60 pressing mechanism    -   61 first opposing section    -   71 chip seal    -   72 chip seal    -   73 chip seal

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below withreference to the drawings.

Embodiment 1 of the Invention

A compressor according to Embodiment 1 is a rotary compressor forcompressing fluid by expanding and contracting volume in a cylinderchamber described later by eccentrically rotating an eccentric rotationbody. This rotary compressor is connected to, for example, arefrigeration circuit for an air conditioner and is used for compressingthe refrigerant sucked from an evaporator and discharging it to acondenser.

As shown in FIG. 1, the rotary compressor (1) is so composedhermetically as a whole that a compression mechanism (20) and anelectric motor (a drive mechanism) (30) are accommodated in a casing(10).

The casing (10) is composed of a cylindrical body portion (11), an upperhead (12) fixed to the upper end of the body portion (11), and a lowerhead (13) fixed to the lower end of the body portion (11). An intakepipe (14) passing through the upper head (12) is provided in the upperhead (12). A discharge pipe (15) passing through the body portion (11)is provided in the body portion (11).

The compression mechanism (20) is provided in the upper part of thecasing (10). The compression mechanism (20) is arranged between an upperhousing (16) and a lower housing (a support plate) (17) which are fixedto the casing (10). The compression mechanism (20) includes a cylinder(21) having a cylinder chamber (C1, C2) having annular shapes in sectionat a right angle in the axial direction, an annular piston (piston) (22)arranged in the cylinder chamber (C1, C2), and a blade (23) whichdefines the cylinder chamber (C1, C2) into high pressure chambers(compression chambers) (C1-Hp, C2-Hp) serving as first chambers and lowpressure chambers (intake chambers) (C1-Lp, C2-Lp) serving as secondchambers (see FIG. 2). Further, a cylinder side end plate (26A) isformed at the lower end of the cylinder (21) so as to face the cylinderchamber (C1, C2). Wherein, the cylinder (21) rotates eccentrically as aneccentric rotation body in the present embodiment.

In the lower part of the casing (10), the electric motor (30) isprovided which includes a stator (31) and a rotor (32). The stator (31)is fixed to the inner wall of the body portion (11) of the casing (10).The rotor (32) is connected to a drive shaft (33) so as to rotate thedrive shaft (33) in association with the rotation of the rotor (32).

The drive shaft (33) extends in the vertical direction to the vicinityof the upper head (12) from the vicinity of the lower head (13). An oilsupply pump (34) is provided at the lower end of the drive shaft (33).The oil supply pump (34) is connected to an oil supply passage (notshown in the drawing), which extends upward within the drive shaft (33)and communicates with the compression mechanism (20). The oil supplypump (34) supplies lubricant oil reserved in the bottom of the casing(10) to a sliding section of the compressor (20) through the oil supplypassage.

An eccentric portion (33 a) is formed at a part of the drive shaft (33)located inside the cylinder chamber (C1, C2). The eccentric portion (33a) has a diameter larger than the upper part and the lower part of thedrive shaft (33) and is eccentric from the axial center of the driveshaft (33) by a predetermined distance.

The cylinder (21) includes an outer cylinder (24) and an inner cylinder(25). The outer cylinder (24) and the inner cylinder (25) are connectedat the lower ends thereof with each other to be integral by means of thecylinder side end plate (26A). The inner cylinder (25) is slidablyfitted at the eccentric portion (33 a) of the drive shaft (33).

The annular piston (22) is formed integrally with the upper housing (16)and includes a piston side end plate (26B). Bearing portions (16 a, 17a) for supporting the drive shaft (23) are formed at the upper housing(16) and the lower housing (17), respectively. Thus, the compressor (1)of the present embodiment has a construction in which the drive shaft(33) passes in the vertical direction through the cylinder chamber (C1,C2) and the eccentric portion (33 a) is held at both ends in the axialdirection thereof to the casing (10) by means of the bearing portions(16 a, 17 a).

In the compression mechanism (20), the cylinder side end plate (26A) isarranged at one end in the axial direction (the lower end) of thecylinder chamber (C1, C2) so as to face the lower end face in the axialdirection of the piston (22) while the piston side end plate (26B) isarranged at the other end in the axial direction (the upper end) of thecylinder chamber (C1, C2) so as to face the upper end face in the axialdirection of the cylinder (21).

As shown in FIG. 2, the compression mechanism (20) includes a swing bush(27) for movably connecting the annular piston (22) and the blade (23)with each other. The annular piston (22) is formed in a C-shape intowhich a part of an annular shape is divided. The blade (23) extends onthe line in the radial direction of the cylinder chamber (C1, C2) fromthe wall face on the inner peripheral side of the cylinder chamber (C1,C2) (the outer peripheral face of the inner cylinder (25)) to the wallface on the outer peripheral side thereof (the inner peripheral face ofthe outer cylinder (24)) so as to pass through the divided part of theannular piston (22), and is fixed to the outer cylinder (24) and theinner cylinder (25). The swing bush (27) connects the piston (22) andthe blade (23) with each other at the divided part of the annular piston(22). It is noted that the blade (23) may be formed integrally with theouter cylinder (24) and the inner cylinder (25) or may be formed byintegrating a separate member with both the cylinders (24, 25).

The inner peripheral face of the outer cylinder (24) and the outerperipheral face of the inner cylinder (25) are cylindrical facesarranged coaxially, and the cylinder chamber (C1, C2) is formedtherebetween. The annular piston (22) has an outer peripheral face ofwhich diameter is smaller than that of the inner peripheral face of theouter cylinder (24) and an inner peripheral face of which diameter islarger than that of the outer peripheral face of the inner cylinder(25). Whereby, an outer cylinder chamber (C1) is formed between theouter peripheral face of the annular piston (22) and the innerperipheral face of the outer cylinder (24) while the inner cylinderchamber (C2) is formed between the inner peripheral face of the annularpiston (22) and the outer peripheral face of the inner cylinder (25).

Further, in the state that the outer peripheral face of the annularpiston (22) is substantially in contact at one point thereof with theinner peripheral face of the outer cylinder (24) (strictly, in the statethat though there is a gap on the order of microns therebetween, leakageof refrigerant in the gap is ignorable), the inner peripheral face ofthe annular piston (22) is substantially in contact at one point 180°different in phase from the contact point with the outer peripheral faceof the inner cylinder (25).

The swing bush (27) is composed of a discharge side bush (27A) locatedon the high pressure chamber (C1-Hp, C2-Hp) side with respect to theblade (23) and an intake side bush (27B) located on the low pressurechamber (C1-Lp, C2-Lp) side with respect to the blade (23). Thedischarge side bush (27A) and the intake side bush (27B) have the sameshape of substantially a semicircle in section and are arranged so as toface each other at the flat faces thereof. The space between theopposing faces of the bushes (27A, 27B) serves as a blade groove (28).

The blade (23) is inserted in the blade groove (28) so as tosubstantially be in face contact with the flat faces of the swing bushes(27A, 27B) while the circular outer peripheral faces of the swing bushes(27A, 27B) are substantially in face contact with the annular piston(22). The swing bushes (27A, 27B) allows the blade (23) to move back andforth in the direction along the face thereof in the blade groove (28)with the blade (23) inserted in the blade groove (28). Also, the swingbushes (27A, 27B) are capable of rocking integrally with the blade (23)relative to the annular piston (22). Accordingly, the swing bush (27) isso composed that the blade (23) and the annular piston (22) are capableof rocking relatively with the center point of the swing bush (27) as arocking center and the blade (23) is capable of moving back and forth inthe direction along the face of the blade (23) with respect to theannular piston (22).

It is noted that the bushes (27A, 27B) are separated in the presentembodiment but may be integral by connecting parts thereof with eachother.

In the above described construction, when the drive shaft (33) rotates,the outer cylinder (24) and the inner cylinder (25) rock with the centerpoint of the swing bush (27) as a rocking center while the blade (23)moves back and forth in the blade groove (28). This rocking motion makesthe cylinder (21) to rotate (revolve) eccentrically with respect to thedrive shaft (33) (see FIG. 3(A) to FIG. 3(D)).

As shown in FIG. 1, an intake port (41) is formed in the upper housing(16) under the intake pipe (14). The intake port (41) ranges wide fromthe inner cylinder chamber (C2) to an intake space (42) formed outsidethe outer cylinder (24). The intake port (41) passes through the upperhousing (16) in the axial direction thereof to allow the low pressurechambers (C1-Lp, C2-Lp) of the cylinder chamber (C1, C2) and the intakespace (42) to communicate with an upper space (a low pressure space(S1)) above the upper housing (16). In the outer cylinder (24), athrough hole (43) is formed for allowing the intake space (42) tocommunicate with the low pressure chamber (C1-Lp) of the outer cylinderchamber (C1). Also, a through hole (44) for allowing the low pressurechamber (C1-Lp) of the outer cylinder (C1) to communicate with the lowpressure chamber (C2-Lp) of the inner cylinder chamber (C2) is formed inthe annular piston (22).

Discharge ports (45, 46) are formed in the upper housing (16). Thedischarge ports (45, 46) pass through the upper housing (16) in theaxial direction thereof. The lower end of the discharge port (45) opensto the high pressure chamber (C1-Hp) of the outer cylinder chamber (C1)while the lower end of the discharge port (46) opens to the highpressure chamber (C2-Hp) of the inner cylinder chamber (C2). On theother hand, the upper ends of the discharge ports (45, 46) communicatewith a discharge space (49) through discharge valves (reed valves) (47,48) for opening/closing the discharge ports (45, 46), respectively.

The discharge space (49) is formed between the upper housing (16) and acover plate (18). A discharge passage (49 a) for allowing the dischargespace (49) and the space (a high pressure space (S2)) below the lowerhousing (17) to communicate with each other is formed through the upperhousing (16) and the lower hosing (17).

As one of the features of the present invention, a pressing mechanism(60) for bringing the cylinder side end plate (26A) and the piston sideend plate (26B) close to each other in the axial direction of the driveshaft (33) is provided between the cylinder side end plate (26A) and thelower housing (17). Specifically, the pressing mechanism (60) iscomposed of a sealing ring (29) provided at an opposing part between thelower housing (17) and the cylinder side end plate (26A). The sealingring (29) is fitted in an annular groove (17 b) formed in the lowerhosing (17) and defines the opposing part between the cylinder side endplate (26A) and the lower hosing (17) into an opposing section (a firstopposing section) (61) on the inner side in the radial direction of thesealing ring (29) and an opposing section (a second opposing section)(62) on the outer side in the radial direction of the sealing ring (29).

The sealing ring (29) is arranged eccentrically to the aforementioneddischarge ports (45, 46) away from the center of the cylinder (21)fitted in the eccentric portion (33 a) of the drive shaft (33) (see FIG.2). In detail, the center of the sealing ring (29) is eccentric withinthe range between 270° and 360° where the angle is measured in thedirection of rotation (the clockwise direction in the presentembodiment) of the eccentric rotation body (the cylinder (21) in thepresent embodiment) from the direction (the X axis shown in FIG. 2)extending along the blade (23) from the center of the drive shaft (33)as a reference angle (0°).

In the above construction, when refrigerant compressed in the cylinderchamber (C1, C2) of the compression mechanism (20) is discharged to thehigh pressure space (S2), the pressure of the refrigerant works on thelower face of the cylinder side end plate (26A) composing the firstopposing section (61) through a gap between the drive shaft (33) and thebearing portion (17 a). The first opposing section (61) also receivespressure of the lubricant oil in the casing (10). As a result, upwardpressing force in the axial direction works on the cylinder side endplate (26A). Wherein, the sealing ring (29) is arrange eccentricallyfrom the center of the cylinder (21) and the center of the drive shaft(33), so that the axial-direction pressing force works also on a part ofthe cylinder side end plate (26A) which is eccentric from the center ofthe cylinder (21). In other words, in the pressing mechanism (60), apart eccentric from the center of the cylinder side end plate (26A) thatthe cylinder (21) includes is the center of the point of action of theaxial-direction pressing force.

Further, the rotary compressor (1) of the present embodiment includes asealing mechanism for minimizing a gap in the axial direction betweenthe cylinder (21) and the annular piston (22) for the purpose ofpreventing the fluid from leaking in the gap. Specifically, the sealingmechanism includes an annular first chip seal (71) provided at a part (afirst axial-direction gap) between the upper end face (the end face inthe axial direction) of the outer cylinder (24) and the lower face ofthe piston side end plate (26B) and an annular second chip seal (72)provided at a part (a first axial-direction gap) between the upper endface (the end face in axial direction) of the inner cylinder (25) andthe lower face of the piston side end plate (26B). The sealing mechanismalso includes a third chip seal (73) provided at a part (a secondaxial-direction gap) between the lower end face (the end face in axialdirection) of the annular piston (22) and the upper face of the cylinderside end plate (26A).

-Driving Operation-

Driving operation of the rotary compressor (1) will be described nextwith reference to FIG. 3.

When the electric motor (30) starts operating, rotation of the rotor(32) is transmitted to the outer cylinder (24) and the inner cylinder(25) of the compression mechanism (20) through the drive shaft (33). Asa result, the blade (23) is in reciprocal motion (moves back and forth)between the swing bushes (27A, 27B) while rocking integrally with theswing bushes (27A, 27B) relative to the annular piston (22). Then, theouter cylinder (24) and the inner cylinder (25) revolve while rockingrelative to the annular piston (22) to allow the compression mechanism(20) to perform a predetermined compression process.

Referring to the outer cylinder chamber (C1), the cylinder (21) in thestate shown in FIG. 3(D) where the low pressure chamber (C1-Lp) hassubstantially a minimum volume revolves in the clockwise direction inthe drawing to allow the refrigerant to be sucked from the intake port(41) to the low pressure chamber (C1-Lp). Then, the refrigerant issucked from the intake space (42) communicating with the intake port(41) to the low pressure chamber (C1-Lp) through the through hole (43).When the cylinder (21) revolves to change its state from the state shownin FIG. 3(A) to FIG. 3(B) and to FIG. 3(C) in this order, and then, tothe state shown in FIG. 3(D) again, the sucking of the refrigerant tothe low pressure chamber (C1-Lp) terminates.

At this point, the low pressure chamber (C1-Lp) becomes the highpressure chamber (C1-Hp) where the refrigerant is compressed whileanother low pressure chamber (C1-Lp) is formed with intervention of theblade (23). When the cylinder (21) further rotates from this state, therefrigerant sucking is repeated in the newly-formed low pressure chamber(C1-Lp) while the volume of the high pressure chamber (C1-Hp) decreasesto compress the refrigerant in the high pressure chamber (C1-Hp). Then,when the pressure of the high pressure chamber (C1-Hp) becomes apredetermined value and the pressure difference from the discharge space(49) reaches a set value, the discharge valve (47) is opened by therefrigerant at high pressure in the high pressure chamber (C1-Hp) toallow the refrigerant at high pressure to flow out into the highpressure space (S2) from the discharge space (49) through the dischargepassage (49 a).

Referring to the inner cylinder chamber (C2), the cylinder (21) in thestate shown in FIG. 3(B) where the low pressure chamber (C2-Lp) hassubstantially a minimum volume revolves in the clockwise direction inthe drawing to allow the refrigerant to be sucked from the intake port(41) to the low pressure chamber (C2-Lp). Then, the refrigerant issucked from the intake space (42) communicating with the intake port(41) to the low pressure chamber (C2-Lp) through the through hole (44).When the cylinder (21) revolves to change its state from the state shownin FIG. 3(C) to FIG. 3(D) and to FIG. 3(A) in this order, and then, tothe state shown in FIG. 3(B) again, the sucking of the refrigerant tothe low pressure chamber (C2-Lp) terminates.

At this point, the low pressure chamber (C2-Lp) becomes the highpressure chamber (C2-Hp) where the refrigerant is compressed whileanother low pressure chamber (C2-Lp) is formed with intervention of theblade (23). When the cylinder (21) further rotates from this state, therefrigerant sucking is repeated in the newly-formed low pressure chamber(C2-Lp) while the volume of the high pressure chamber (C21-Hp) decreasesto compress the refrigerant in the high pressure chamber (C2-Hp). Then,when the pressure of the high pressure chamber (C2-Hp) becomes apredetermined value and the pressure difference from the discharge space(49) reaches a set value, the discharge valve (48) is opened by therefrigerant at high pressure in the high pressure chamber (C2-Hp) toallow the refrigerant at high pressure to flow out into the highpressure space (S2) from the discharge space (49) through the dischargepassage (49 a).

In this way, the refrigerant at high pressure compressed by the outercylinder chamber (C1) and the inner cylinder chamber (C2) and flowing inthe high pressure space (S2) is discharged from the discharge pipe (15),undergoes the condensation process, the expansion process, and theevaporation process in the refrigeration circuit, and then, is suckedagain into the rotary compressor (1).

-Operation of Pressing Mechanism-

Operation of the pressing mechanism (60), which is the significantfeature of the present invention, will be described next with referenceto FIG. 3.

In the compression process of the above described rotary compressor (1),when the refrigerant becomes at high pressure in the cylinder chamber(C1, C2), the pressure of the refrigerant at high pressure works as athrust load (PT) on the cylinder side end plate (26A) in the axialdirection. If the thrust load (PT) would become large or the point ofaction of the thrust load (PT) would be away from the drive shaft (33),a turnover moment, which is caused due to the thrust load (PT), may begenerated to turn over the cylinder (21) as the eccentric rotation body.

Under the circumstances, in the rotary compressor (1) of the presentembodiment, pressing force in the axial direction is generated to workagainst the thrust load (PT), thereby reducing the turnover moment.

Specifically, when the cylinder (21) is in the state shown in FIG. 3(A),the refrigerant in the high pressure chamber (C1-Hp) of the outercylinder chamber (C1) becomes at high pressure, and accordingly, thethrust load (PT) works on a part near the high pressure chamber (C1-Hp)away from the center of the cylinder (21). On the other hand, thearrangement of the sealing ring (29) between the cylinder side end plate(26A) and the lower housing (17) as described above allows the pressureof the refrigerant at high pressure to work on the lower face of thecylinder side end plate (26A) in the first opposing section (61) togenerate the axial-direction pressing force (P) pushing the cylinderside end plate (26A) upward against the piston (22) in contrast to thethrust load (PT). The sealing ring (29) is arranged eccentrically to thedischarge ports (45, 46) away from the center of the cylinder (21), sothat the axial-direction pressing force (P) obtained from the pressingmechanism (60) works also on a part near the discharge ports (45, 46)away from the center of the cylinder (21). Hence, the point of action ofthe axial-direction pressing force (P) readily agrees with the point ofaction of the thrust load (PT) in the radial direction, reducing theturnover moment effectively.

When the cylinder (21) is in the state shown in FIG. 3(B), therefrigerant in the high pressure chamber (C1-Hp) of the outer cylinderchamber (C1) or the high pressure chamber (C2-Hp) of the inner cylinderchamber (C2) becomes at high pressure to allow the thrust load (PT) towork on a part near the high pressure chamber (C1-Hp) away from thecenter of the cylinder (21). In this state, also, the axial-directionpressing force (PT) from the pressing mechanism (60) works on a partnear the discharge ports (45, 46) away from the center of the cylinder(21), with a result that the point of action of the axial-directionpressing force (P) readily agrees with the point of action of the thrustload (PT) in the radial direction, reducing the turnover momenteffectively.

As well, when the cylinder (21) is in the state shown in FIG. 3(D), therefrigerant in the high pressure chamber (C2-Hp) of the inner cylinderchamber (C2) becomes at high pressure to allow the thrust load (PT) towork on a part near the high pressure chamber (C2-Hp) away from thecenter of the cylinder (21). In this state, also, the axial-directionpressing force (PT) works on a part near the discharge ports (45, 46)away from the center of the cylinder (21), with a result that the pointof action of the axial-direction pressing force (P) readily agrees withthe point of action of the thrust load (PT) in the radial direction,reducing the turnover moment effectively.

-Effects of Embodiment 1-

The following effects are exhibited in Embodiment 1.

In the present embodiment, the axial-direction pressing force (P)obtained from the pressing mechanism (60) against the cylinder side endplate (26A) works on a part near the discharge ports (45, 46) away fromthe center of the cylinder (21) where the thrust load (PT) is liable towork in the cylinder chamber (C1, C2). This brings the point of actionof the axial-direction pressing force (P) close to the point of actionof the thrust load (PT), reducing the turnover moment effectively.

The pressing mechanism (60) can be easily attained by arranging thesealing ring (29) between the cylinder side end plate (26A) and thelower housing (17). In other words, the aforementioned turnover momentcan be reduced effectively with the simple construction.

Further, the pressing mechanism (60) brings the cylinder side end plate(26A) close to the piston side end plate (26B) in the axial direction tominimize the first axial-direction gaps and the second axial-directiongap between the cylinder (21) and the piston (22), preventing therefrigerant from leaking in the axial-direction gaps. Hence, thecompression efficiency of the rotary compressor can be increased.

In addition, in Embodiment 1, the plurality of chip seals (71, 72, 73)are provided in the first axial-direction gaps and the secondaxial-direction gap between the cylinder (21) and the piston (22),respectively, thereby further preventing the fluid from leaking in theaxial-direction gaps between the cylinder (21) and the piston (22) tofurther increase the compression efficiency.

-Modified Example 1 of Embodiment 1-

Modified Example 1 of Embodiment 1 will be described next. ModifiedExample 1 is different from Embodiment 1 in the position of the sealingring (29). Specifically, the sealing ring (29) in this modified exampleis fitted in an annular groove (17 b) formed in the lower face portionof the cylinder side end plate (26A), as shown in FIG. 4, in contrast tothe sealing ring (29) in Embodiment 1 which is fitted in the annulargroove (17 b) formed in the lower housing (17). Wherein, the sealingring (29) is arranged eccentrically 20 to the discharge ports (45, 46)away from the center of the cylinder (21), similarly to that inEmbodiment 1.

In Modified Example 1, also, the axial-direction pressing force (P)obtained from the pressing mechanism (60) less separates from the thrustload (PT) in the radial direction, as shown in FIG. 4(A) to FIG. 4(D),reducing the turnover moment effectively.

-Modified Example 2 of Embodiment 1-

Modified Example 2 of Embodiment 1 will be described next. ModifiedExample 2 is different from Embodiment 1 in the form of the pressingmechanism (60). Specifically, a slit (63) is formed as the pressingmechanism (60) in Modified Example 2.

As shown in FIG. 5, the slit (63) is formed in the lower face portion ofthe cylinder side end plate (26A) in Modified Example 2. The slit (63)is formed eccentrically to the discharge ports (45, 46) away from thecenter of the cylinder (21). When the pressure of the refrigerant athigh pressure works on the slit (63), pressure gradient is generated toallow the axial-direction pressing force eccentric to the dischargeports (45, 46) (leftward in FIG. 5) away from the center of the cylinder(21) to work on the cylinder side end plate (26A). Thus, the point ofaction of the axial-direction pressing force (P) in the cylinder sideend plate (26A) can be brought close to the point of action of thethrust load (PT), reducing the turnover moment effectively.

Furthermore, the slit (63) can be formed easily by forming a step in thecylinder side end plate (26A). This means that the slit (63) can beeasily formed in forming the cylinder (21) and the cylinder side endplate (26A) integrally, for example, by sintering or forging.

-Modified Example of Embodiment 1-

Modified Example 3 of Embodiment 1 will be described next. ModifiedExample 3 is different from Embodiment 1 and Modified Example 2 inconstitution of the pressing mechanism (60). Specifically, through holes(64) and grooves (65) which are formed in the cylinder side end plate(26A) are utilized as the pressing mechanism (60) in Modified Example 3.

In Modified Example 3, two through holes (64) and two grooves (65) areformed in the cylinder side end plate (26A), as shown in FIG. 6.Specifically, the through holes (64) are an outer through hole (64 a)communicating with the outer cylinder chamber (C1) and an inner throughhole (64 b) communicating with the inner cylinder chamber (C2). On theother hand, the grooves (65) are an outer grove (65 a) communicatingwith the outer through hole (64 a) and an inner groove (65 b)communicating with the inner through hole (65 b). Each of the grooves(65) and the through holes (64 b) is formed eccentrically to thedischarge ports (45, 46) away from the center of the cylinder (21).

In the above construction, when the refrigerant is compressed in thecylinder chamber (C1, C2), the refrigerant at high pressure flows intothe respective grooves (65) through the respective through holes (64).When the refrigerant flows in the respective grooves (65), the pressureof the refrigerant works on the respective grooves (65). In this way, inModified Embodiment 3, part of the refrigerant compressed in thecylinder chamber (C1, C2) is allowed to flow into the grooves (65) andthe pressure of the refrigerant is utilized, thereby obtaining theaxial-direction pressing force pushing upward the cylinder side endplate (26A). The thus obtained axial-direction pressing force (P) workson a part near the discharge ports (45, 46) away from the center of thecylinder (21), reducing the turnover moment effectively.

Further, in Modified Example 3, the pressure of the refrigerantcompressed in the cylinder chamber (C1, C2) is utilized as the pressingmechanism (60), and accordingly, the axial-direction pressing force (P)working on the grooves (65) increases as the thrust load (PT) isincreased in association with an increase in pressure in the cylinderchamber (C1, C2). In contrast, the axial-direction pressing force (P)decreases as the thrust load (PT) is decreased. Thus, the mechanicalloss of the eccentric rotation body caused due to surplusaxial-direction pressing force (P) is prevented from increasing,implementing effective reduction in turnover moment.

Moreover, in Modified Example 3, the upper openings of the through holes(64) are blocked by the lower end of the piston (22) according torevolution of the cylinder (21), enabling adjustment of the opening ofthe upper openings. By the adjustment, the opening of the upper openingsof the through holes (64) can be made small to reduce excessivepressure, for example, when the pressure in the cylinder chamber (C1,C2) rises to excessively increase the pressure working on the grooves(65). On the contrary, when the pressure working on the grooves (65)becomes insufficient due to a decrease in pressure, for example, in thecylinder chamber (C1, C2), the opening of the upper openings of thethrough hoes (64) can be made large to increase the pressure. In thisway, the pressure in the cylinder chamber (C1, C2), which variesaccording to the position of the cylinder (21) in revolving motion, isbalanced with the opening of the through holes (64), attaining optimumadjustment of the axial-direction pressing force (P) working on thegrooves (65).

Embodiment 2 of the Invention

In Embodiment 2 of the present invention, the annular piston (22)rotates eccentrically as the eccentric rotation body in contrast to theEmbodiment 1 in which the cylinder (21) rotates eccentrically as theeccentric rotation body.

In Embodiment 2, as shown in FIG. 7, the compression mechanism (20) isarranged in the upper part of the casing (10), similarly to that inEmbodiment 1. The compression mechanism (20) is arranged between theupper housing (16) and the lower housing (17), similarly to that inEmbodiment 1.

The outer cylinder (24) and the inner cylinder (25) are provided in theupper housing (16), which is the difference from Embodiment 1. The outercylinder (24) and the inner cylinder (25) are integrated with the upperhousing (16), thereby forming the cylinder (21). The cylinder side endplate (26A) is integrally formed at the upper ends of the outer cylinder(24) and the inner cylinder (25).

The annular piston (22) is held between the upper housing (16) and thelower hosing (17). The piston side end plate (26B) is integrally formedwith the lower end of the annular piston (22). A hub (26 a) is providedat the piston side end plate (26B) so as to be silidably fitted to theeccentric portion (33 a) of the drive shaft (33). Accordingly, in thisconstruction, when the drive shaft (33) rotates, the annular piston (22)rotates eccentrically in the cylinder chamber (C1, C2). The blade (23)is formed integrally with the cylinder (21), similarly to that inEmbodiment 1.

In the upper housing (16), there are formed an intake port (41) allowingthe low pressure space (S1) above the compression mechanism (20) in thecasing (10) to communicate with the outer cylinder chamber (C1) and theinner cylinder chamber (C2), the discharge port (45) for the outercylinder chamber (C1), and a discharge port (46) for the inner cylinderchamber (C2). The intake space (42) communicating with the intake port(41) is formed between the hub (26 a) and the inner cylinder (25) whilethe through hole (44) and the through hole (43) are formed in the innercylinder (25) and the annular piston (22), respectively.

The cover plate (18) is provided above the compression mechanism (20) sothat the discharge space (49) is formed between the upper housing (16)and the cover plate (18). The discharge space (49) communicates with thehigh pressure space (S2) below the compression mechanism (20) throughthe discharge passage (49 a) formed through the upper housing (16) andthe lower housing (17).

In the construction in Embodiment 2, the sealing ring (29) is arrangedbetween the piston side end plate (26B) and the lower hosing (17). Thesealing ring (29) is arranged eccentrically to the discharge ports (45,46) away from the center of the annular piston (22) as the eccentricrotation body. Further, the pressing mechanism (60) is so composed thatmakes the axial-direction pressing force works on a part eccentric tothe discharge ports (45, 46) away from the center of the annular piston(22) in the piston side end plate (26B).

In Embodiment 2, the axial-direction pressing force (P) generated by thepressing mechanism (60) readily agrees with the thrust load (PT), whichis generated eccentrically to the discharge ports (45, 46) away from thecenter of the annular piston (22), when the annular piston (22) is inthe revolving motion in the order from FIG. 8(A) to FIG. 8(D), therebyreducing the turnover moment with respect to the annular piston (22)effectively.

The sealing ring (29) is provided in the lower housing (17) in FIG. 7while the sealing ring (29) is provided in the piston side end plate(26B) in FIG. 8 as a modified example thereof, wherein the respectivepressing mechanisms (60) operate in the same fashion.

Embodiment 3

In Embodiment 3 of the present invention, the low pressure space (S1)and the high pressure space (S2) which are partitioned by thecompression mechanism (20) in the casing (10) are arranged in reverse tothose in Embodiments 1 and 2.

Specifically, in Embodiment 3, as shown in FIG. 9, the intake pipe (14)passes through the body portion (11) and the discharge pipe (15) passesthrough the upper head (12). The intake pipe (14) communicates with thelow pressure space (S1) formed below the compression mechanism (20)while the discharge pipe (15) communicates with the high pressure space(S2) formed above the compression mechanism (20).

The low pressure space (S1) communicates with the intake space (42)extending from the lower housing (17) to the upper housing (16). Theintake space (42) communicates at the middle part in the axial directionthereof with the cylinder chamber (C1, C2) through the respectivethrough holes (43, 44) in the outer cylinder (24) and the piston (22).Further, the intake space (42) communicates at the upper end thereofwith the intake port (41) formed in the upper housing (16). The intakeport (41) communicates with the cylinder chamber (C1, C2), similarly tothat in Embodiments 1 and 2. On the other hand, the high pressure space(S2) communicates with the discharge space (49) through a dischargepassage not shown.

Moreover, in Embodiment 3, a high pressure introducing passage (66) isformed so as to extend from the upper housing (16) to the annular piston(22). The high pressure introducing passage (66) has an upper endopening formed between two discharge valves (47, 48) and a lower endopening at the lower end in the axial direction of the annular piston(22). A through hole (64) is formed in the cylinder (21) so as tocommunicate with the lower end opening of the high pressure introducingpassage (66). The through hole (64) extends in the axial direction up tothe opposing part between the cylinder side end plate (26A) and thelower housing (17). Further, two sealing rings (29) are provided besidethe through hole (64) in the lower end portion. The two sealing rings(29) define the opposing part between the cylinder side end plate (26A)and the lower housing (17) into three opposing sections. Of the opposingsections, an annular opposing section interposed between the two sealingrings (29) serves as the first opposing section (61) that communicateswith the through hole (64).

In the above described construction, the refrigerant at high pressurecompressed in the compression mechanism (20) and discharged in thedischarge space (49) is introduced into the first opposing section (61)through the high pressure introducing passage (66) and the through hole(64). As a result, the pressure of the refrigerant at high pressureworks on the cylinder side end plate (26A) in the first opposing section(61). The sealing rings (29) are arranged eccentrically to the dischargeports (45, 46) away from the center of the cylinder (21), so that theaxial-direction pressing force working upward on the cylinder side endplate (26A) works on a part eccentric to the discharge ports (45, 46)away from the center of the cylinder (21). Accordingly, as describedabove, the turnover moment caused due to the thrust load can be reducedeffectively.

Furthermore, the sealing mechanism is so composed that the cylinder (21)is pushed towards the annular piston (22) in the axial direction tominimize the axial-direction gaps between the cylinder (21) and theannular piston (22) by using the sealing rings (29), resulting inprevention of the refrigerant in the cylinder chambers (C1, C2) fromleaking.

-Modified Example of Embodiment 3-

A modified example of Embodiment 3 will be described next with referenceto FIG. 10. In this modified example, the low pressure space (S1) isformed below the compression mechanism (20) while the high pressurespace (S2) is formed above the compression mechanism (10), similarly tothe case in Embodiment 3, but the upper housing (16) in this modifiedexample is different from that in Embodiment 3.

In the upper housing (16) of this modified example, the discharge space(49) is formed wider in radial direction than that in Embodiment 3.Further, a discharge passage (49 a) allowing the high pressure space(S2) and the discharge space (49) to communicate with each other isformed substantially coaxially with the drive shaft (33).

Moreover, the upper housing (16) is not fixed to the inner wall of thebody portion (10) and is held by engaging with a plurality of pins (67)provided at the upper face on the outer peripheral side of the lowerhousing (17). Further, in this modified example, a chip seal (71) isprovided between the lower end face of the annular piston (22) and theupper face of the cylinder side end plate (26A).

In the above construction, the sealing mechanism for pushing upwards inthe axial direction the upper housing (16) and the annular piston (22)towards the cylinder (21) is so composed that the pressure of therefrigerant at high pressure in the high pressure space (S2) is allowedto work on the wall face of the upper housing (16) facing the dischargespace (49). Accordingly, the axial-direction gaps between the cylinder(21) and the annular piston (22) can be minimized.

Moreover, in this modified example, almost similarly to, for example,Modified Example 3 of Embodiment 1, the pressing mechanism (60) is socomposed that a through hole (64) and a groove (65) are formed in thecylinder (22) to allow the refrigerant at high pressure in the cylinderchambers (C1, C2) to work on the groove (65). In this case, also, thepressing mechanism (60) reduces the turnover moment in the cylinder(21).

Other Embodiments

The present invention has the following variations on the aboveembodiments.

In Embodiment 1, the center of the sealing ring (29) provided in thelower housing (17) is located eccentrically to the discharge ports (45,46) away from the center of the cylinder (21). However, the center ofthe sealing ring (29) may be located eccentrically to the dischargeports (45, 46) away from the center of the lower housing (17), namely,away from the center of the drive shaft (33). In this case, also, theaxial-direction pressing force can be centered at a part near thedischarge ports (45, 46) so that the point of action of theaxial-direction pressing force (P) can be brought close to the point ofaction of the thrust load (PT). Hence, the turnover moment can bereduced.

In the above embodiments, the pressing mechanism (60) for allowing theaxial-direction pressing force to work on the cylinder side end plate(26A) or the piston side end plate (26B) is applied to the rotarycompressor (1) including the two cylinder chambers (C1, C2). However,the pressing mechanism (60) is applicable to other rotary compressors(1).

A rotary compressor (1) shown in FIG. 11, for example, includes acylinder (21) having a cylinder chamber (C) in a circular shape insection at a right angle in the axial direction and a piston (22) in acircular shape arranged in the cylinder chamber (C). The cylinderchamber (C) is defined by a blade not shown into a first chamber (C-Hp)and a second chamber (C-Lp). Further, the cylinder side end plate (26A)facing the inside of the cylinder chamber (C) is formed at the upper endof the cylinder (21) while the piston side end plate (26B) facing at apart thereof the inside of the cylinder chamber (C) is formed at thelower end of the piston (22).

In the above construction, also, the axial-direction pressing forceobtained by providing the sealing ring (29) or the like is madeeccentric away from the center of the piston (22) to prevent separationof the point of action of the axial-direction pressing force from thepoint of action of the thrust load in the radial direction, therebyreducing the turnover moment effectively.

In addition, in the above embodiments, the axial-direction pressingforce is obtained from the high pressure in the high pressure space(S2), the pressure (medium pressure) in the cylinder chamber (C1, C2),or the like. While, the axial-direction pressing force is obtainablefrom the pressure in the low pressure space (S1), for example, in suchmanner that the high pressure in the high pressure space (S2) isintroduced to the low pressure space (S1) through a pressure adjustingvalve or the like so that the pressure in the low pressure space (S1)becomes at medium pressure.

It is noted that the above embodiments are substantially preferredexamples and are not intended to limit the scope of the presentinvention, applicable objects thereof, and applicable range thereof.

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful especially forrotary compressors in which the turnover moment is liable to work on aneccentric rotation body such as a piston, a cylinder, and the like.

1. A rotary compressor, comprising: a compression mechanism including acylinder having a cylinder chamber, a piston accommodated in thecylinder chamber eccentrically with respect to the cylinder, and a bladearranged in the cylinder chamber and defining the cylinder chamber intoa first chamber and a second chamber, at least one of the cylinder andthe piston rotating eccentrically as an eccentric rotation body; a driveshaft configured for driving the compression mechanism; a pressingmechanism configured for bringing a cylinder side end plate, which isprovided at one end in an axial direction of the cylinder chamber andfaces an end face in an axial direction of the piston, and a piston sideend plate, which is provided at the other end in the axial direction ofthe cylinder chamber and faces an end face in an axial direction of thecylinder, close to each other in an axial direction of the drive shaft;and a casing configured for accommodating the compression mechanism, thedrive shaft, and the pressing mechanism, the pressing mechanism beingeccentric away from a center of the cylinder side or the piston side endplate of the eccentric rotation body, and the pressing mechanismgenerating an axial-direction pressing force with a center of thepressing mechanism being eccentric away from a center of the driveshaft.
 2. The rotary compressor of claim 1, wherein the cylinder chamberhas a circular shape when viewed perpendicularly from the axialdirection, and the piston is substantially circular.
 3. The rotarycompressor of claim 1, wherein the cylinder chamber has an annular shapewhen viewed perpendicularly from the axial direction, and the pistonincludes a substantially annular piston arranged in the cylinder chamberand defining the cylinder chamber into an outer cylinder chamber and aninner cylinder chamber.
 4. The rotary compressor of claim 3 wherein thepiston has a gap dividing the piston into a C-shape with a swing bushingslidably held in the gap, and forming a blade groove configured forholding the blade so as to allow the blade to move back and forth in theswing bushing, and the blade is disposed in the blade groove so as toextend from a wall face on an inner peripheral side to a wall face on anouter peripheral side of the annular cylinder chamber.
 5. The rotarycompressor of claim 1, wherein the compression mechanism has a pluralityof discharge ports configured for discharging fluid compressed in thecylinder chamber to an outside of the compression mechanism, and thepressing mechanism generates a pressing force in the axial direction thepressing mechanism having a center that is eccentric to the dischargeports away from a center of the cylinder side or piston side end plateof the eccentric rotation body.
 6. The rotary compressor of claim 1,wherein the pressing mechanism has a support plate that is arrangedalong a side of the cylinder side or the piston side end plate of theeccentric rotation body, a sealing ring for defining a first opposingsection between the cylinder side or the piston side end plate and thesupport plate on an inner side in a radial direction and a secondopposing section between the cylinder side end plate and the supportplate on an outer side in the radial direction, the sealing ring isarranged eccentrically away from a center of the eccentric rotation bodyin one of the cylinder side end plate, the piston side end plate of theeccentric rotation body and the support plate, and the pressingmechanism allows a fluid pressure discharged outside the compressionmechanism to work on the first opposing section.
 7. The rotarycompressor of claim 6, wherein the sealing ring is fitted in an annulargroove formed in one of the eccentric rotation body and the supportplate.
 8. The rotary compressor of claim 1, wherein the cylinder has aslit that is formed at a portion eccentric from a center of theeccentric rotation body in a face portion opposite a face on a cylinderchamber side of the cylinder side end plate of the eccentric rotationbody, and the pressing mechanism allows pressure of fluid dischargedoutside the compression mechanism to work on the slit.
 9. The rotarycompressor of claim 1, wherein the cylinder side has a groove and athrough hole the groove is formed in a portion eccentric from a centerof the eccentric rotation body on a face opposite a face on a cylinderchamber side of the end plate of the eccentric rotation body, thethrough hole is formed in the cylinder side end plate for allowing thegroove to communicate with the cylinder chamber, and the pressingmechanism introduces a portion of fluid compressed in the cylinderchamber into the groove through the through hole to allow a pressure ofthe fluid to work on the groove.
 10. The rotary compressor of claim 1,further comprising: a sealing mechanism configured and arranged topresent leakage of fluid in at least one of a first axial direction gapbetween an end face in the axial direction of the cylinder and thepiston side end plate and a second axial direction gap between an endface in the axial direction of the piston and the cylinder side endplate.
 11. The rotary compressor of claim 10, wherein the sealingmechanism includes a chip seal provided at least one of the first axialdirection gap and the second axial direction gap.